1. Field of the Invention
The present invention relates to a signal processing apparatus, a signal processing system, and a signal processing method.
2. Description of the Related Art
Mobile terminals exemplified by mobile phones frequently include a movable member as a connecting portion between an operation portion operated by a user and a display portion in which information is displayed. For example, an opening/closing structure of a folding mobile phone is typical of such a movable member. Further, in addition to the calling and mail functions, recent mobile phones have a viewing function of images or an imaging function, and thus it is necessary for the connecting portion to be movable complexly in accordance with usage of the user. When the viewing function of images is used, for example, the user desires to direct the display portion toward the user and the operation portion unnecessary for viewing put away. Thus, a structure allowing the orientation or position of the display portion to change in accordance with usage thereof when a mobile phone is used as an ordinary phone, used as a digital camera, used as a TV set and the like is demanded.
As a matter of fact, a large number of signal lines and power lines are wired through the connecting portion between the operation portion and display portion. For example, several tens of wires are connected in parallel in the display portion. Thus, if a movable member capable of making complex motions described above is used as a connecting portion, reliability and the like of such wires will significantly decrease. For such reasons, technology used is being shifted from the parallel transmission method to the serial transmission method to reduce the number of signal lines in the connecting portion. Naturally, a technological shift for similar reasons is not limited to the world of mobile phones and occurs in the world of various electronic devices in which complex wiring is needed. In addition to the above reason, serialization also aims to reduce electromagnetic noise (EMI: Electro Magnetic Interference).
In the serial transmission method, transmission data is transmitted after being encoded according to a predetermined method. For example, the NRZ (Non Return to Zero) coding mode, Manchester coding mode, or AMI (Alternate Mark Inversion) coding mode is used as the coding mode. The Manchester coding mode is a mode in which a bit value is represented by transitioning of a signal level from a high level to a low level or from a low level to a high level within a cycle. Further, Japanese Patent Application Laid-Open No. 2006-5651 describes, in the Manchester coding mode, a technology to represent a plurality of bit values within a cycle by varying the high level while the low level being fixed.